Final answer:
In reproductive strategies, sperm-depleted male fruit flies are known to pick larger, more fecund females to maximize reproductive efficiency when sperm is limited, which demonstrates a natural selection influence in their behavior.
Step-by-step explanation:
Studies using the common fruit fly, Drosophila melanogaster, have revealed important aspects of energy allocation in reproductive strategies. Sexual reproduction often involves a trade-off between energy expended on mating and the individual's survivability. Males that are sperm-depleted have been found to choose larger, more fecund females, which is an energy efficient strategy to maximize the chances of their genes being passed on when their reproductive resource—sperm—is limited. Conversely, females might shift energy away from reproduction towards survival when energy resources are low, indicating different reproductive cost strategies between sexes.
This behavior is a clear example of natural selection influencing reproductive behavior. Those genes that predispose males to pick more fecund females when sperm is limited ensure more efficient use of their remaining reproductive resources, thus offering a better chance of successful offspring. This aspect of behavioral biology, or ethology, helps us understand the evolutionary factors shaping such behaviors.